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Molecular cloning of a novel gene involved in serotonin receptor‐mediated signal transduction in rat stomach
Author(s) -
Ohya Susumu,
Takii Takemasa,
Yamazaki Hiroko F.,
Matsumori Miki,
Onozaki Kikuo,
Watanabe Minoru,
Imaizumi Yuji
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01485-8
Subject(s) - signal transduction , cloning (programming) , serotonin , transduction (biophysics) , 5 ht receptor , receptor , gene , microbiology and biotechnology , molecular cloning , biology , chemistry , genetics , biochemistry , gene expression , computer science , programming language
In Xenopus oocytes injected with small size mRNAs (500–700 b), obtained from rat stomach by fractionation, application of 10 μM 5‐HT induced a substantial Ca 2+ ‐activated Cl − current (I Cl‐Ca ). I Cl‐Ca was not elicited by 5‐HT in native oocytes. Consistent results from this assay in the oocyte expression system motivated cDNA cloning experiments. A novel cDNA (named at tomach erotonin receptor‐related cDNA: RSS cDNA) which encodes a small protein involved in specific 5‐HT receptor‐mediated I Cl‐Ca activation was identified. The molecular weight of RSS protein in the reticulocyte lysate translation system (∼10 kDa) is identical to that calculated from the amino acid sequence. Computer‐aided analysis of the predicted protein does not show any obvious sequence homologies (<18%) to any other proteins including G protein‐coupled receptors. Northern analysis revealed that RSS mRNA is ubiquitously expressed at varying levels in a number of different tissues. Furthermore, the binding of [ 3 H]spiperone, a 5‐HT 2 receptor antagonist, was examined in CHO cells, which highly expressed RSS transcripts (named CHO‐RSS). Specific binding of [ 3 H]spiperone was not clearly observed in native CHO but was detected in CHO‐RSS. The dissociation constant was 10.3 nM in CHO‐RSS. These results suggest that RSS protein may be a factor which facilitates 5‐HT receptor expression or, alternatively, an enhancer of the affinity of native 5‐HT receptor to 5‐HT.